Origin of AIDS

John,
Actually, Gallo dod not have that mich trouble finding cells in which
HIV could replicate. he found that CD4 positive T cells would support
replication of the virus. The problem was that the virus killed the
cells so rapidly that he was unable to establish long term cultures
for study. Gallo eventually isolated persistently infected cells from
continuos cell lines which suppoerted replication of the virus but
were relatively refractory to the cytopathic effects of the virus.
As far as the HIV-polio link, even if HIV was present in Salk's cells,
this virus could never have survived the inactivation process used by
Salk. HIV is not a particularly stable virus. SV-40, on the other
hand, is remarkably stable to chemical and physical incativation used
at the time.
The genetic links between HIV visna etc., have been looked at.
Phylogenetic trees are available in many reviews which shows little
similarity between these virus at either the sequence level or genetic
organization level (e.g. the types of regulatory genes found in these
viruses).
Jay Mone'